2009 1.8TDi Focus judders in 3rd/4th gear goes into limp mode with traction symbol light......

[Proctor]

Alright guys, new member, had plenty cars but pretty green with knowledge.

Bought a 2009 1.8tdi focus estate ex police a week ago private sale just as a runabout to chuck crap into, haven't driven it anywhere till yesterday. Took it along the bypass noticed at high 3rd and 4th a slight judder intermitent, nothing car shaking but similar to how when you are running out of fuel but not quite as prolonged, just small hiccups of power loss at higher revs, not hammering it though. Carried on, got to a hill stretched out 3rd gear and went into limp mode "engine malfunction" along with the traction symbol (I assume, orange light with car skidding). This happened 3 or 4 times in 3rd and 4th. I took it to a premium used car lot that a relative works at and got it plugged into diagnostics and the log suggested something to do with the 3rd cylinder injector and they qouted me some ridiculous cost to replace the pair almost as high as what I paid for the car so I left it. I asked why the traction warning light was the only symbol to appear and they suggested just one of those things and wasnt the cause of the problem.

Was down a parts shop today returning some bits and an old boy mechanic was there and overheard me picking brains of a chap there, he said its the traction system triggering limp mode and nothing to do with injector, I then visted my usual garage and they suggested its probably something to do with the saftey system.

Now whats more likely? these diagnositc systems being acurate (could it be a false postive) or should I trust the warning light as the source of the fault, I assume the fix for the latter would be much cheaper than replacing the cylinder injectors whcih I certianly won't do.

Anyone have any input on this, what exactly is happening, have I got too much torque for my tyres causing the juddering, no grip?

Any input greatly appreciated, i'm tempted to just ditch it stating the fault and be done with it but would liek to salvage if its not too costly.